Fluke Rev. 4 user manual Providing Loop Power, Documenting Process Calibrator, Using Source Mode

Documenting Process Calibrator

Using Source Mode

Providing Loop Power

The calibrator provides loop power at 28V or 24V dc. The 28V setting provides enough current for two or three 4-20 mA devices on the loop in addition to the two-wire transmitter but uses more battery power. Use the 24V setting if there are two or fewer loads on the loop in addition to the two-wire transmitter. (Each device on a typical 4- to 20-mA loop has a resistance of 250Ω, thus dropping 5V at 20 mA. A typical transmitter must have 11V minimum in order to operate correctly at its top end.)

When loop power is enabled, the mA (middle column) jacks are dedicated to sourcing and measuring the current loop. This means that the SOURCE mA, measure RTD, and measure and source Ω functions are not available (see Table 8, later in this manual.)

Connect the calibrator in series with the instrument current loop as Figure 16 shows. Proceed as follows to source loop power:

1. Press sfor smode.

2.Note that following Loop Power, Disabled is highlighted. Press e.

3.Use the uor darrow keys to select Enabled 24V or Enabled 28V.

4.Press e.

5.Press the Done softkey.

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